1. Field of the Invention
The present invention relates to an engine brake unit having a combined oil passage, more particularly, to an engine brake unit having a combined oil passage, in which a single oil passage structure is produced by combining an engine brake oil passage and a lubricating oil passage together in such a manner that an engine brake can be operated by the single oil passage structure.
2. Description of Related Art
Engine braking generally refers to the act of slowing down a vehicle by down-shifting to a lower transmission gear. In engine braking, however, an excessive amount of load is applied to respective parts of an engine when a transmission is down-shifted. This may cause drawbacks such as reduced engine lifetime.
Accordingly, a conventional engine brake was devised, which can improve the effect of engine braking by opening an exhaust port of a cylinder at the end of compression stroke so that power stroke does not occur or by maintaining the exhaust port to be partially open so that compression stroke does not occur.
Below, a description will be given of a conventional engine brake with reference to the accompanying drawings.
FIG. 1A is a perspective view illustrating part of a conventional engine brake unit.
The conventional engine brake unit is a compression release engine brake, which opens an exhaust port 30 at the end of compression stroke so that power stroke does not occur. In the conventional engine brake unit, an actuator 40 located inside a valve bridge 35 serves to press the exhaust valve 30 by hydraulic pressure generated by brake oil.
At this time, a brake oil passage 11 supplying brake oil for operating the actuator 40 and a lubricating oil passage 12 for supplying oil to prevent engine parts from being damaged by lessening friction, are separately formed in a rocker shaft 10 and a rocker arm 20.
Such a conventional art has a complicated construction of oil passages since the lubricating oil passage and the brake oil passage are separately formed in the rocker shaft and the rocker arm. The problem of the conventional art is inefficiency.
FIG. 1B is a perspective view illustrating part of another conventional engine brake unit.
The engine brake unit of another conventional art is a full-cycle engine brake, which maintains an exhaust valve 30 to be opened so that compression stroke does not occur. Such an engine brake has a separate housing 50, inside of which an actuator 40 is installed so that the exhaust valve 30 can maintain a pressurized state due to oil pressure generated by brake oil.
Brake oil is fed to respective parts and a solenoid valve 60 through one passage formed in a rocker shaft 10. Brake oil is supplied from the solenoid valve 60 to the housing 50.
However, such a conventional engine brake unit has problems such as an increase in weight and production cost due to an increase in the number of parts since the housing, inside of which the actuator of the engine brake is stored, is additionally provided.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.